Wash, peel, and grate the bottle gourd. You can also chop it very finely. If you cannot manage very thin chopping then you will have to steam the gourd before adding it to the oil. (Reserve the peels to make lau er khosha bhaja)
Heat oil in a pan. Fry boris until golden brown. Remove onto a kitchen towel and set aside.
To the same oil, add green chilies and mustard. As they start to splutter, add the grated bottle gourd. Add salt, sugar and give everything a good stir. Cover and cook, stirring occasionally, for 10 minutes or until the bottle gourd has softened.
Adjust salt and sugar, add grated coconut, ghee and fried boris. Stir and remove from heat.